1. Field of the Invention
The present invention relates to an image-reading apparatus reading image information on a document optically and an image-forming apparatus equipped with the image-recording device.
2. Description of the Related Art
Image-reading apparatus have been used in image-forming apparatus such as copying machine, printer, and facsimile and also independently as monofunctional devices. Among these image-reading apparatus, there are some devices, in the housing of which information on a document is read by scanning of the document surface with a movable optical unit that is placed movably.
In such an image-reading apparatus, the movable optical unit is generally locked, for example, with a locking member in the housing, for prevention of dislocation of the optical unit by vibration or impact during shipment from production factory and damage thereof in the housing for example by collision to the wall. The movable optical unit has been locked inside the image-reading apparatus. For that reason, it was difficult for the user to unlock it, and thus, it was unlocked, for example, by a service engineer, when the image-reading apparatus was installed.
In the recent trend toward reduction in size, such an image-reading apparatus is carried or transported by the user more frequently. The user brings such an image-reading apparatus, for example, on change of address or redecoration of room.
However as described above, it was difficult for the user to lock or unlock the movable optical unit in conventional image-reading apparatus, resulting in increase in the possibility of damage of the movable optical units. In addition, it was necessary for example for a service man to visit the user after transportation of the image-reading apparatus for prevention of damage before it happens.
Under the circumstances above, proposed were many image-reading apparatus of which the movable optical unit could be locked and unlocked easily by the user. For example, Japanese Unexamined Patent Publication No. hei 7-92575 (D1) discloses a device in which the movable optical unit is locked and unlocked by using a removable operation lever that is operated as inserted from outside the housing.
Alternatively, Japanese Examined Patent Publication No. hei 7-104558 (D2) and Japanese Unexamined Patent Publication No. hei 7-240821 (D3) disclose devices in which the movable optical unit is locked and unlocked, as a screw or the like is inserted from outside the housing in the direction identical with the travelling direction of the movable optical unit. Yet alternatively, Japanese Unexamined Patent Publication No. hei 9-289571 (D4) discloses a device in which the movable optical unit is locked and unlocked by using a clip in the direction perpendicular to the travelling direction of the movable optical unit at the terminal of the movable optical unit opposite to its home position. Yet alternatively, Japanese unexamined patent publication 2001-235810 (D5) discloses a device in which the movable optical unit is held with a lifting-detecting rod and a revolving arm by operation to lift the housing.
However, in the device described in Literature D1, although the movable optical unit may be easily unlocked, it is quite difficult for the user to lock the unit once again, because an operation lever should be pushed into the housing carefully after complete understanding of the internal device structure.
Alternatively in the devices described in literatures D2 and D3, because the optical unit is locked and unlocked in the direction identical with the travelling direction of the movable optical unit, the movable optical unit may be dislocated easily by the pressure, for example from a screw, especially during locking, leading to deterioration in operability. In the device described in literature D4, in which the optical unit is locked and unlocked by a clip independent from the device main body, there is a concern about disappearance of the clip itself. Further, the device described in literature D5, which contains members such as lifting-detecting rod and revolving arm, will not satisfy the recent demand for reduction in size.